1. Field of the Invention
The subject invention is directed to fuel nozzles that provide a controlled spray pattern and, more particularly, to means for filtering fluid flow through such nozzles.
2. Description of the Prior Art
As well known in the art, fuel nozzles generally include a nozzle tip in combination with a holder. The nozzle tip, by its particular structure, determines and controls the spray pattern. The nozzle tip is mounted in the holder which provides fluid flow to the nozzle tip and positions the tip at a particular location and orientation.
Conventional nozzle tips generally include a body having a discharge orifice at one end, and an internal member that swirls the fluid flowing to the orifice. Typically, this member is referred to as a swirl plug and accomplishes the swirling action through various arrangements of vanes, slots, or passageways. Nozzle tips having a dual circuit, that is, a primary and secondary flow path, generally further include a second body concentrically located in the first body and having a primary spray orifice located adjacent to the discharge orifice of the outer body. In these nozzles, the swirl plug is typically located in a cavity in the primary body. In any case it is important to secure the swirl plug firmly in the nozzle tip to prevent leakage at the metal-to-metal seal face between the swirl plug and the body. This leakage can cause unacceptable deviations in flow calibration and spray pattern.
In some nozzle tips, the swirl plug is secured by being press fitted or otherwise permanently fastened to the body. However, it is preferred that the swirl plugs be removably secured in the nozzle tip so that the nozzles are capable of being serviced. Thus, various types of coil springs, spring washers and other mechanisms for retaining the swirl plug in the nozzle tip have been developed in the prior art.
Also in the prior art, many mechanisms for filtering the fluid flowing to various types of nozzles are known. For example, filters are sometimes placed at the inlet to the nozzle holder. However, it is preferable to locate the filter as close to the nozzle tip as possible so that it can filter out any chips or other particles remaining in the nozzle from its manufacture or installation. Most preferably, the filter is located adjacent to the nozzle tip so that it will also filter out carbon particles or other contaminants that develop in the upstream portions of the nozzle during its use.
However, in the prior art, the structure of the nozzle tip often allowed insufficient space to accommodate the filter. In the subject invention, it was recognized that a filter that could retain the swirl plug would simplify the nozzle tip by eliminating the need for separate coil springs or other means for retaining the swirl plug. Thus, such a filter could be located in a preferred position inside the nozzle tip.